Flow divider valve



FLOW DIVIDER VALVE Filed Feb. 5, 1965 FLOW DIVIDER VALVE 10 LOAD -1 LOAD-2 Q/ L g 26 2.6 50% -24 ,-zo l g INVENTOR. PETER SIDLES, JR.

ATTORNEYS United States Patent 3,348,563 FLOW DIVIDER VALVE Peter Sidles, Jr., North Aurora, 11]., assignor to Caterpillar Tractor Co., Peoria, 111., a corporation of California Filed Feb. 3, 1965, Ser. No. 430,065 2 Claims. (Cl. 137-101) ABSTRACT OF THE DISCLOSURE A flow divider valve for fluids constructed to enable a disproportionate flow of fluid from a single source into two circuits in response to difference in pressure in the circuits.

Commonly known flow dividers are use-d to ensure substantially equal flow to two circuits irrespective of varying loads or back pressures in the circuits. However, such systems have the disadvantage that only half of the pump flow is available for actuation of either circuit and this results in poor response of the load creating mechanism. There are many applications using flow dividers where fluid under pressure is used to actuate two separate devices not commonly used at the same time. Thus, by directing a greater portion of the total flow to the device which is most heavily loaded, its response time may be appreciably reduced with corresponding improvement in speed and efliciency of operation. With such disproportionate flow, it is also possible to maintain the desired speed and efliciency of operation of a single circuit and yet the pump size may be reduced with commensurate economic savings. For example, in a track-type tractor where two steering clutches are both actuated from a single pressure source, but are not frequently used at the same time, a greater part of the volume may be diverted to the most heavily loaded clutch to improve its rate of response. It is, therefore, the object of the present invention to provide a flow divider valve for use between a source of fluid under pressure and two potential load creating mechanisms which is responsive to a higher back pressure from either of said mechanisms to direct a greater volume of fluid thereto. Further objects and advantages of the invention are made apparent in the following specification wherein it is described in detail by reference to the accompanying drawings.

In the drawings:

FIG. 1 is a schematic view of apparatus representing a typical environment in which the flow divider of the present invention might be used; and

FIG. 2 is a schematic cross section of a flow divider valve embodying the present invention.

In FIG. 1, a pump is shown as directing hydraulic fluid from a reservoir 11 through a flow divider valve generally indicated at 12 and thence through separate circuits to two load producing devices represented as load 1 and load 2. These devices may be considered a control valve and a servo for a fluid motor controlled thereby. The valves are of the open-center type and when they are in neutral position substantially unrestricted flow passes both devices and is communicated to the reservoir by a common line 14. Commonly used flow dividers ensure that a substantially equal volume of fluid is directed toward load 1 and load 2 even when the pressure in the system is varied by closing one of the valves. This ensures equal volumes of fluid for the actuation of both devices simultaneously. Consequently, only half the volume of the pump is available for the actuation of either device. With the present invention, the flow divider is of the disproportionate type and since it is not expected that both devices will be actuated at the same time, substantially the entire volume of the pump is directed to the device being used so that a smaller pump may be employed and high pressure and high volumeare assured where they are most needed. On the other hand, if both devices are actuated at the Sametime and to the same degree the flow is divided equally and the response of each device is the same such that this capability is maintained as with conventional flow dividers.

The construction of the flow divider valve is shown in FIG. 2 wherein the valve 12 is shown with an inlet 16 and outlets 17 and 18. A bore in the valve which slidably receives a piston 20 communicates between the inlet and the two outlets. Fluid flows from the inlet through radial ports 22 in the piston and an axially extending passage 24. Normally, and with no load creating a back pressure in either of the outlets 17 or 18, the piston 20 will be centrally disposed by balanced pressures against its ends and flow through the unrestricted outlets will be equal.

FIG. 2 illustrates the piston 20 in the position assumed when a device is actuated to place a restriction to flow from the outlet 18 and causing a back pressure against the right end of the piston 24. With known flow dividers which produce substantially equal volume through both outlets, this leftward movement stops when the pressure on the left end of the piston equals that at the right and the volume flowing through both outlets is equal.

The present invention differs from conventional flow dividers in that a cylindrical projection 26 is provided'at each end of the bore in which the piston slides and is positioned to be embraced by the passage 24 in the piston as it moves in either direction. This creates a restriction shown at 30 which is upstream of a restriction shown at 32 also created by axial movement of the piston. As a consequence of the upstream restriction 30 a pressure drop occurs between the passage 24 and the space beyond the end of the piston. This pressure drop permits continued leftward movement of the piston until the orifice 32 is smaller than the orifice 30 permitting pressure to rise at the end of the piston until it equals pressure at the right end of the piston. Consequently, the piston is balanced only after it has traveled a greater distance than in ordinary flow dividers and the volume of flow at the right hand end greatly exceeds that at the left hand end where all flow passes the orifices 30 and 32. As is apparent, the ratio of flow through the two outlets can be varied by changing the configuration-that is to say, the diameter and length of the cylindrical projections 26. The operation just described is, of course, identical in principle when a load is imposed which creates a higher back pressure in the outlet 17 and the piston 24 moves in the opposite direction.

I claim:

1. In a flow divider for use between a source of fluid under pressure and two separate circuits which comprises, a body having an inlet receiving fluid under pressure and two outlets communicating with said circuits, said body having a bore communicating with the inlet and both outlets, a piston reciprocal in said bore and having passages communicating between the inlet and the Outlets at each end of the piston, the improvement which comprises an element at at least one end 0 fthe bore positioned to be embraced by the passage at one end of the bore as the piston moves toward it in response to pressure from its opposite end to restrict flow through the bore and create a pressure drop causing continued movement of the piston until flow past its ends and t0 the outlets is of unequal volume and in which the passages at the ends of the piston are cylindrical and said element is of cylindrical configuration with a diameter smaller than the UNITED STATES TATENTS 1,993,790 3/1935 Kinsella 137l0l 2,242,002 5/1941 Klein l371()1 2,685,294 8/1954 Gold 1371 2,932,316 4/1960 Stanton 137-51625 WILLIAM F. ODEA, Primary Examiner.

passage which embraces it, the passages in the piston in- 15 W. H. WRIGHT, Assistant Examiner. 

1. IN A FLOW DIVIDER FOR USE BETWEEN A SOURCE OF FLUID UNDER PRESSURE AND TWO SEPARATE CIRCUITS WHICH COMPRISES, A BODY HAVING AN INLET RECEIVING FLUID UNDER PRESSURE AND TWO OUTLETS COMMUNICATING WITH SAID CIRCUITS, SAID BODY HAVING A BORE COMMUNICATING WITH THE INLET AND THE OUTLETS OUTLETS, A PISTON RECIPROCAL IN SAID BORE AND HAVING PASSAGES COMMUNICATING BETWEEN THE INLET AND THE OUTLETS AT EACH END OF THE PISTON, THE IMPROVEMENT WHICH COMPRISES AN ELEMENT AT AT LEAST ONE END OF THE BORE POSITIONED TO BE EMBRACED BY THE PASSAGE AT ONE END OF THE BORE AS THE PISTON MOVES TOWARD IT IN RESPONSE TO PRESSURE FROM ITS OPPOSITE END TO RESTRICT FLOW THROUGH THE BORE AND CREATE A PRESSURE DROP CAUSING CONTINUED MOVEMENT OF THE PISTON UNTIL FLOW PAST ITS ENDS AND TO THE OUTLETS IS OF UNEQUAL VOLUME AND IN WHICH THE PASSAGES AT THE ENDS OF THE PISTON ARE CYLINDRICAL AND SAID ELEMENT IS OF CYLINDRICAL CONFIGURATION WITH A DIAMETER SMALLER THAN THE PASSAGE WHICH EMBRACES IT, THE PASSAGES IN THE PISTON INCLUDING A COAXIAL CYLINDRICAL PASSAGE THROUGHOUT ITS FULL LENGTH. 